1. Field of the Invention
The present invention relates to an in-vehicle illumination device and, more specifically, to an improved illumination device serving both as a room lamp and a map lamp.
2. Description of the Related Art
In a vehicle, a roof section is provided with an illumination device for illuminating the inside of the vehicle during the night, for example. For use as such an illumination device, commercially available is the one incorporated not only with a room lamp but also a map lamp, which is used for illumination of limited range of area. There is also an illumination device offering indirect lighting with the high rendering effect. An example includes Patent Document 1 (Japanese Patent No. 3959917). Also commercially available is an illumination device integrally provided with a mirror (vanity mirror).
FIGS. 11A to 11C each show an exemplary illumination device with a light source being an LED (Light-Emitting Diode) lamp. FIG. 11A is a front view of an illumination device 100, FIG. 11B is a cross sectional view of the illumination device 100 cut along a line A-A, and FIG. 11C is another cross sectional view of the illumination device 100 cut along a line B-B. In such an illumination device 100, a light from an LED lamp 101 is guided into a light guide plate 102. The light is then emitted from a front surface 103 of the light guide plate 102 so that the inside of a vehicle is illuminated thereby (room lamp illumination). On the other hand, a light from an LED lamp 104 is converged by a lens 105 so that the resulting light illuminates any limited portion of area, i.e., like spotlight (map lamp illumination).
Patent Documents 1 to 3 each describe an exemplary improved technology for the in-vehicle illumination device. Patent Document 1 describes a technology for achieving improvement in terms of design with a provision of function of indirect lighting. Patent Document 2 (JP-A-2006-7856) and Patent Document 3 (JP-A-2006-232092) each describe a technology for achieving improvement of easy visual recognition of switches.